The present invention relates to a fixation pin for use in retaining small-bone fragments in an osteosynthesis procedure.
It is generally known in osteosyntheses to fix bone fragments by screws or pins. In the case of small-bone splinterings, the screws or pins available in the prior art are, however, much too large to fix a small splintered portion of a given bone to another portion of the same bone without damaging these parts. The fixing of such small bone fragments by means of simple pins or nails is therefore problematical, since there is no abutment to hold the parts together, and the bone may shift on the outer wall of the pin or nail.
More specifically, the use of Kirschner wires (K-wires) in small-bone and bone-fragment fixation dates back to the early part of this century and is a common procedure in orthopedics, offering advantages of simplicity of use, and low cost. Threaded K-wires, designed to produce better anchorage in bone, were a later modification. And small-fragment screws, using the lag-screw principle were in wide use in the 1970's, to provide rigid fixation of small fragments. However, all of these techniques had their disadvantages.
K-wires offer poor purchase; a fragment can slide with respect to a wire. Any bending of a wire, as for securing purposes, may result in displacement or fracture of a fragment. And wire migration into a joint through the skin carries the risk of infection.
Threaded K-wires have only a small distal threaded portion, which can improve anchorage to the main or larger bone fragment to which a smaller fragment is to be re-united; but most of the disadvantages of the K-wire remain.
Use of the lag-screw technique involves a more complex procedure; two drill sizes are required for pre-drilling, and there must be a pretapping of bone. This technique is not suitable for small bone fragments, and there is risk of bone contamination.